Rotary type motor with flexible drive means to reciprocate cutters for cutting sheet material



May 26, 1970 I K. RENGER 3,513,544

ROTARY TYPE MOTOR WITH FLEXIBLE DRIVE MEANS TO RECIPROCATE GUTTERS FOR cuwwme SHEET MATERIAL Filed Sept. 15. 1967 3 Sheets-Sheet 1 /nvemor; Kar l R EN GE R his A ffor-ney May 26, 1970 K. RENGER 3,51

ROTARY TYPE MQTOR WITH FLEXIBLE DRIVE MEANS To RECIPROCATE CUTTERS FOR CUTTING SHEET MATERIAL Filed Sept. l5, 1967 3' Sheets-Sheet 5 lnvemo/i' Karl RENGER by: M a m his Aflomey United States Patent O 3,513,544 ROTARY TYPE MOTOR WITH FLEXIBLE DRIVE MEANS T RECIPROCATE CUTTERS FOR CUT- TING SHEET MATERIAL Karl Renger, Rommelshausen, Germany, assignor to Krauss u. Reichert Spezialmaschinenfabrik u. Apparatebau, Fellbach, Germany, a firm Filed Sept. 15, 1967, Ser. No. 668,011 Int. Cl. B26b 7/00 US. Cl. 30-272 10 Claims ABSTRACT OF THE DISCLOSURE A motor-driven machine having a reciprocating cutting blade which is adapted to cut through a stack, composed of layers of sheet material, during vertical reciprocation of the cutting blade. A guide means guides the blade for reciprocating movement and a motor is provided for driving a rotary crank means. A connecting rod extends between and is operatively connected with the crank means and the blade for converting rotary movement of the crank means into reciprocating movement of the blade. This connecting rod is made of a springy bendable material and preferably takes the form of an elongated leaf spring which is fixed at one end to a crank pin of the rotary crank means and at its opposite end to the blade. As a result of the springy bendability of the leaf spring which forms the connecting rod, the machine is of light weight and is capable of high-speed, smooth operation.

Background of the invention The present invention relates to motor-driven machines for cutting sheet material.

Such machines conventionally include a crank drive for converting the rotary movement of the motor into reciprocating movement of the cutting blade which is guided by a suitable guide means of the machine for reciprocating movement.

With conventional cutting machines of this type the use of a conventional crank drive results in a bu ky, relatively large structure which is relatively heavy, so that the portable, manually movable cutting machine cannot be operated conveniently. Moreover, the guiding structure which provides the slidable guide for the connection between the crank drive and the blade is subjected to. a high degree of wear and requires constant maintenance as well as relatively large masses which are to be moved.

Summary of the invention It is thus a primary object of the present invention to avoid these drawbacks or at least to greatly minimize them.

In particular it is an object of the present invention to avoid or substantially reduce these drawbacks by way of the structure of the crank drive of the machine of the invention.

It is thus an object of the invention to provide a relatively small machine of light weight which is capable of high speed, smooth operation.

In accordance with the invention these results are achieved by providing between the motor-driven rotary crank means and the reciprocating blade a connecting rod which is made of a springy bendable material and which preferably takes the form of a leaf spring which may be guided in some cases in a suitable gliding gap of a guide means carried by the machine frame in the region of that end of the leaf spring which is connected to the blade.

Brief description of the drawings 'ice The invention is illustrated by way of example in the accompanying drawings which form part of this application and in which:

FIG. 1 is a front elevation of the upper part of a cutting machine of the invention which is illustrated in FIG. 1 with the front cover plate of the housing removed so as to more clearly illustrate the structure within the housing at the upper part of the cutting machine;

FIG. 2 is a partly sectional side view of the structure of FIG. 1 taken along line 2-2 of FIG. 1 in the direction of the arrows; and

FIG. 3 is a fragmentary front elevation of a different embodiment of a crank drive of the machine of FIGS. 1 and 2.

Description of preferred embodiments Referring now to the drawings and in particular to FIGS. 1 and 2, the cutting machine illustrated therein includes a housing composed of part 11a for receiving a crank-drive and part 11b for housing electric motor 10. The axis 13 of the electric motor 10 extends in the manner indicated by the dot-dash line in FIG. 2, and this axis 13- of the motor extends centrally through the rotary crank disc 14 which is coaxially fixed to the motor to be driven thereby. This crank disc 14 forms part of a rotary crank means which includes a bearing 14a carried by the crank disc 14 at a position spaced from the center thereof so that the bearing 14a has a given eccentricity. The rotory crank means further includes a crank pin 15 which is supported for free rotary movement in the bearing 14a so that the crank pin 15 is carried by the disc 14 for rotation therewith about the axis 13, this crank pin 15 is also supported by way of the bearing 14a for free rotary movement with respect to the disc 14. The crank pin 15 is slotted. Thus, the portion of the crank pin 15 which projects beyond the crank disc 14 is formed with a transverse slot 15a extending diametrically through the crank pin 15 inwardly from its outer end.

In order to be able to adjust the stroke of the reciproeating cutting blade which is referred to below, an adjusting means is provided as shown in the embodiment of FIG. 3. For this purpose the bearing 14a is eccentrically carried by a rotary adjusting disc 40. Thus, as may be seen from FIG. 3 the bearing 14a is spaced from the center of the adjusting disc 40. This adjusting disc 40 is itself supported for rotary movement in a circular recess 14b which is formed in the crank disc 14 at its outer face which is visible in FIG. 3 and which is situated at the left of the disc 14 in FIG. 2. The circular recess 14b extends only part of the way through the disc 14 but has a depth which is sufficiently great to situate the exterior surface of the disc 40, which is visible in FIG. 3, at a location where it is flush with the exterior surface of the disc 14. In order to fix the disc 40 in selected angular positions of adjustment with respect to the crank disc 14, the disc 40 is provided at its periphery with equidistant notches 40a, and in the illustrated example there are four notches 40a displaced by with respect to each other about the periphery of the adjusting disc 40.

Screws 41 are threaded into the disc 14 and have enlarged heads which are countersunk into recesses of the disk 14 so that the exterior surfaces of the heads, which are visible in FIG. 3, are flush with the exterior surfaces of the discs 40 and 14 when the screws 41 are threaded all the way into the disc 14. In this latter position of the screws 41 portions of the heads thereof are received in a pair of opposed notches 40a the configuration of which matches the configuration of the exterior periphery of the heads of the screws 41.

Thus, in order to adjust the eccentricity of the crank pin 15, it is only necessary to unscrew the screws 41 until their enlarged heads are displaced beyond the disc 40 after which the latter may be turned to locate different notches 40a in alignment with the screws 41 and the latter can then be returned to the positions where the exterior surfaces of their heads are flush with the exterior surface of the disc 14. Thus, the crank pin 15 can be adjusted between a pair of positions of different eccentricity, respectively, by loosening the screws 41, turning the disc 40 through 90 to situate the other pair of opposed notches 40a in alignment with the screws 41, and then returning the screws 41 to their positions where they are flush with the exterior surface of the disc 14 so that their heads will now retain the disc 40 in its adjusted position.

Of course it is also possible to provide a stepless adjustment. For example, the right part of the disc 14, as viewed in FIG. 3, may threadedly carry a set screw whose end presses against the periphery of the adjusting disc 40, which in this case would not have any notches, so that the disc 40 could be releasably fixed by such a set screw at any desired angular position with respect to the crank disc 14.

The drive is transmitted from the rotary crank means which is formed by the disc 14 and crank pin 15 to the reciprocating cutting blade by way of a connecting rod 16 in the form of a leaf spring which has its upper end situated in the transverse slot 15a of the crank pin 15. The upper end of the connecting rod 16 is fixed to the crank pin in the slot thereof by an unillustrated means such as, for example, by being soldered to the pin 15 in the slot 15a thereof or as by being held therein by a suitable set screw.

At its lower end the connecting rod 16 is fixed to the reciprocating flat cutting blade 30. For this purpose a bolt and nut assembly 29 may be used, or the blade 30 and connecting rod 16 may be integral with each other. A guide means 31 is provided to guide the blade 30 for reciprocating movement, and for this purpose the guide means 31 is in the form of an elongated trough-shaped member in which the elongated edge of blade 30 which is opposed to its cutting edge is sheathed so as to he slidably guided in the guide 31. This guide means 31 is in turn carried by an elongated support member 32 which is bolted to the lower end of the housing part 11a.

This elongated support member 32 is provided at its lower end with an unillustrated foot plate resting on suitable rollers. This rollable foot plate supports the cutting machine for movement during the cutting operations during which the machine is displaced manually through a stack of sheet material, such as a stack of fabric sheets situated on a table along which the machine is manually moved.

The housing part 11a carries a handle 12 by means of which the operator may guide the machine, and in addition the housing is provided with a cover plate 11d which is not shown in FIG. 1.

During rotation of the rotary crank means 14, 15 the connecting rod 16 is moved up and down and is elastical ly deflected, at the same time, to the right and left. However, a second guide means defines a guiding gap A in which the lower end of the connecting rod 16 is guided.

This guide means which defines the gap A includes a pair of rollers 17 and 18 of relatively large diameter which respectively press against opposed side faces of the connecting rod 16, which may advantageously have the form of a leaf spring. The rollers 17 and 18 respectively have axially extending roller shafts 17a and 18a of relatively small diameter, and these shafts, where they project beyond the rollers, are supported for rotary movement in substantialy U-shaped bearings 19 and 20, respectively, which have open ends respectively directed toward the opposed faces of the connecting rod 16. The bearings 19 and 20 are in turn carried by free ends of a pair of swing levers 21 and 22. A pair of pivots 33 and 34 respectively support the swing levers 21 and 22 for swinging movement and are themselves fixedly carried by eyes 35 and 36 which are carried in the interior of the housing at the wall 110 thereof substantially at the junction between the housing parts 11a and 11b. Thus, these supports 35 and 36 extend into the interior of the housing and carry the pivots 33 and 34 on which the levers 21 and 22 are swingable.

A springy elastic means is provided for urging the levers 21 and 22 toward the opposed faces of the connecting rod 16 so as to maintain the rollers 17 and 18 pressing against the opposed faces of the connecting rod 16. This springy elastic means includes layers 27 and 28 in the form of springy elastic plates of rubber or the like, these layers pressing against opposed walls of the housing part 11a and being fixed with bearing blocks 25 and 26 respectively. These bearing blocks 25 and 26 support for swinging movement a pair of lock or pressure levers 23 and 24 which are respectively provided with forked ends which receive the pivot pins 37 and 38 of the bearing blocks 25 and 26. The free ends of the pressure or block levers 23 and 24 are convexly curved and bulge outwardly, and these free ends engage the levers 21 and 22 while compressing the springy elastic layers 27 and 28 so that the levers 23 and 24 are held in the illustrated end positions determined by the shoulders 21a and 22a of the swing levers 21 and 22. Thus, the levers 23 and 24 press against the levers 21 and 22, respectively in such a way that the rollers '17 and 18 press with a predetermined pressure against the opposed side faces of the leaf spring which forms the connecting rod 16 of the invention. In order to eliminate the pressure of the rollers 17 and 18 against the connecting rod 16, the swingable lock-levers 23 and 24 need only be swung upwardly through approximately In FIG. 1 the crank pin 15 is shown at its right end position where it is displaced at its furthest distance to the right of the axis 13, while in FIG. 2 the crank pin 15 is shown at its lower dead center position.

With the above-described crank transmission it is possible to achieve a high-speed drive with a small, light electric motor, so that a substantial reduction in the total weight of the machine can be achieved in this way. It is to be noted, however, that the weight of the connecting rod itself is substantially reduced as compared to conventional constructions. The connection of the connecting rod to the cutting blade, which also may take the form of a leaf spring, is very light and simple. Thus, the leaf spring which forms the connecting rod and that which forms the blade can be manufactured from a single elongated piece of springy sheet material, so that any connections between the cutting blade and the connecting rod are rendered superfluous. Of course, for this construction it is to be assumed that the blade will be made of a material which has a sufficient bendability to function properly as the connecting rod 16.

Because the guiding gap A is defined by the pair of pressure rollers 17 and 18, there is no necessity of straight slidable guiding structures, crossheads, or the like. Slidable guiding structures of this latter type require lubrication and adjustment to eliminate play, so that these latter requirements are eliminated as well as the requirement of the relatively large masses for the components which are slidably guided.

The pressure rollers 17 and 18 which guide the bendable connecting rod :16, have a ratio between their outer and inner diameters selected at such a great value that the rotary turning angle of the rollers, which are turned by frictional engagement with the connecting rod through an angle determined by the stroke imparted to the blade by the crank means, need only extend through an extremely small circumferential distance. In order that this small circumferential distance can be provided by way of rolling movements of the roller shafts 17a and 18a, the radii of these shafts are smaller than the radii of the bearing surfaces of the bearings 19 and 20 engaged by the shafts 17a and 18a. Therefore, for this purpose it is sufficient to provide the bearings 19 and 2.0 which are of substantially U-shaped configuration and which have open ends directed toward the connecting rod.

Thus, it is apparent that with the above-described construction, the details of which may be varied in accordance with the language of the claims without departing from the spirit and scope of the invention, a relatively light-weight machine capable of smooth, high-speed operation is achieved, and the cutting machine can be very conveniently manipulated by the operator and carried about.

What is claimed is:

1. In a motor-driven machine for cutting sheet material,

a housing,

an elongated cutting blade,

a motor operatively mounted in said housing,

rotary crank means rotatably driven by said motor,

a connecting rod having the form of a leaf spring extending between and being connected to said blade at one of its ends and said rotary crank means at the other one of its ends for converting the rotary motion of said crank means into a reciprocating movement of said blade, said other one of said ends of said leaf spring being connected to said crank means so as to rotate jointly therewith through its entire rotary motion, said crank means and leaf spring defining planes which are substantially normal to each other, said leaf spring being made of a springy, bendable material and having a pair of opposite wide sides and a pair of opposite narrow sides, guide means guiding said blade and said leaf spring for reciprocating movement, said guide means including a pair of elastic means respectively disposed between said pair of opposite wide sides of said leaf spring.

2. The combination of claim 1 and wherein said crank means includes a rotary crank dis-c and a, crank pin carried thereby, and adjusting means coacting with said disc and pin for adjusting the extent of eccentricity of said pin.

3. The combination of claim 2 and wherein said adjusting means includes a rotary adjusting disc carried by said crank disc for rotary movement thereon and for rotation therewith, said adjusting disc carrying said crank pin at a location spaced from the center of said adjusting disc, and means for releasably fixing said adjusting disc at selected angular positions on said crank disc so as to adjust the eccentricity of said pin.

4. In a motor-driven machine for cutting sheet material, the combination as set forth in claim 1 and wherein said rotary crank means move in a first plane and said blade moves in a second plane which is substantially normal to said first plane.

5. In a motor-driven machine for cutting sheet material, the combination as set forth in claim 1 and wherein said connecting rod and blade are integrally fixed to each other and form a single member.

6. In a motor-driven machine for cutting sheet ma terial, the combination as set forth in claim 5 and wherein said guide means include a pair of oppositely mounted pressure rollers which bear against said leaf spring and define a guide gap therebetween.

7. The combination of claim 5 and wherein a pair of swing-levers which are respectively situation at opposite sides of said leaf spring respectively carry at free ends thereof bearings which support said rollers for rotary movement, and means urging said levers toward said leaf spring so as to press said rollers against opposed faces thereof.

8. The combination of claim 5 and wherein a pair of swing levers which are respectively situated at opposed sides of said leaf spring support said rollers for rotary movement, and springy, elastic means acting on said levers for urging the latter toward said leaf spring so as to maintain said rollers in positions respectively pressing against opposed faces of said leaf spring.

9. The combination of claim 8 and wherein a housing mounted in said motor-driven machine houses said crank means, leaf spring, rollers, and swing levers, all of which are respectively operatively mounted in said motor-driven machine, said springy, elastic means including layers of springy elastic material pressing against walls of said housing, a pair of pivots respectively connected to said layers, and a pair of pressure levers pivotally carried by said pivots and pressing against said swing levers to maintain the latter in positions where said rollers respectively press against opposed faces of said leaf spring.

10. In a motor-driven machine for cutting sheet material, the combination as set forth in claim 6 and wherein said pair of pressure rollers are supported for rotary movement in substantially V-shaped bearings which have open ends directed toward said leaf spring.

References Cited UNITED STATES PATENTS 841,325 1/1907 King 30273 1,050,961 1/1913 Loyd 74-49 2,945,298 7/1960 Gu ttmann 30272 3,276,118 10/1966 Taylor 30272 3,367,051 2/1968 Tylle 74-49 X 2,323,188 6/1943 Atkinson 143-68 X 2,534,001 12/1950 Couse 14368 X 3,111,147 11/1963 Pollak 14368 X FOREIGN PATENTS 528,672 11/1954 Belgium.

ROBERT C. RIORDON, Primary Examiner T. C. PETERS, Assistant Examiner US. Cl. X.R. 

